1. Field of the Invention:
The present invention relates to an method of and an apparatus for replacing air in a head space in a can which contains a carbonated beverage or the like, with an inert gas, and enclosing the inert gas in the head space.
2. Description of the Prior Art:
In the canning industry, it has been customary to replace air in a head space in a can with an inert gas such as a carbon dioxide gas, a nitrogen gas, or the like in a head space in a can, and enclose the inert gas in the head space in order to prevent the quality of preserved contents of the can from being lowered. According to one known method disclosed in Japanese Patent Publication No. 57-29331, an inert gas is injected into a head space in a can barrel filled with contents to replace air in the head space with the inert gas, and then a cap end is mounted on and fixed to the can barrel by seaming.
FIG. 5 of the accompanying drawings shows a can end or cap A having a circular panel a and a cylindrical peripheral wall b depending from the entire periphery of the panel a. The peripheral wall b is fitted over and soldered to an end of a cylindrical can barrel or body B which is filled with contents. If an inert gas is introduced into the can of FIG. 5 by a conventional inert gas filling apparatus, then it is necessary to replace the head space in the can barrel B and also an internal space in the can cap A with the inert gas. It takes a long period of time to replace both spaces with the inert gas even if the amount of the inert gas to be injected and the pressure under which the inert gas is to be injected are carefully controlled. Moreover, the injected inert gas tends to fail to reach every corner of the can cap A and the can barrel B.